[ 380 ] 

 LXI. Intelligence and Miscellaneous Articles, 



IMPROVEMENTS IN MAGNETICAL APPARATUS BY THE REV. 

 W. SCORESBY. 



AT the meeting of the British Association, held in Bristol, in 1836, 

 the Rev. "W . Scoresby made a communication to the Physical 

 Section, on an improved mode of construction in magnetic needles 

 for compasses, &c. by the combination in a parallel series, not in 

 contact, of several thin plates of tempered steel. A variation in- 

 strument, which he at that time exhibited, constructed on this prin- 

 ciple, was stated to have a far greater directive energy than any in- 

 strument, of the nature of a compass, previously constructed. Since 

 that period Mr. Scoresby has been pursuing, as opportunity offered, 

 an extensive series of investigations on the subject ; both as to the 

 law of combination in steel plates and bars, and as to the effect of 

 temper, thickness, &c. on the aggregate power ; with the view of 

 producing more powerful instruments for determining the delicate 

 variations in, and the actual condition of, the earth's magnetism ; 

 a subject now engaging attention in some of the principal observa- 

 tories in Europe. The results, which have been successful beyond 

 the objects originally contemplated, have been recently communicated 

 to the Institute of France. One of these results likely to be of much 

 importance in magnetical science, to which it is extensively appli- 

 cable, is that of producing permanent artificial magnets of almost 

 unlimited power. On the principle of construction of compound 

 magnets hitherto adopted, only a very limited number of bars could 

 be combined with advantage, in consequence of the great deteriora- 

 tion of power occasioned by the condition of violence. Mr. Scoresby 

 found, on combining very superior plates of tempered steel of two 

 feet in length and about ^\h of an inch in thickness that the 

 first six plates received so much power that no additions, however 

 great the number, were capable of producing more, in the aggregate, 

 than about double that power. Aiming, however, to counteract the 

 tendency to such rapid deterioration, Mr. Scoresby made some mag- 

 netical combinations oi perfectly hard steel plates, (which he has a 

 ready method of magnetizing and testing,) by means of which an al- 

 most unlimited power can be obtained. Already this combination has 

 been carried, with no inconsiderable augmentation of the aggregate 

 energy, to the very last, to the extent of several dozens of hard plates, 

 15 inches in length, so as to produce, by such combination, a com- 

 pound magnet of very extraordinary power for its mass. The appli- 

 cation of this principle to apparatus for magnetic electricity will 

 obviously be of much advantage for compactness and power ; whilst 

 the application of the discovery to variation needles, dipping needles, 

 and, probably, to sea compasses also, promises to be of much im- 

 portance in experimental science, as well as for practical and oeco- 

 nomical purposes. Mr. Scoresby's investigations have also led to 

 other practical results, such as the means of testing most rigidly the 

 quality and temper of steel plates, and of bars intended for com- 

 pound magnets on the ordinary construction, by which the best 



